Data transmitting device and data transmitting and receiving system

ABSTRACT

A data transmitting device is for transmitting data including video image information that is inter-frame encoded. The data transmitting device includes an identification information inserting unit configured to insert, in the data to be transmitted by the data transmitting device, video image identification information for identifying the video image information included in the data; and a video image information inserting unit configured to insert the video image information in the data to be transmitted by the data transmitting device. The video image information inserting unit inserts in the data the video image information that has been inter-frame encoded, behind the video image identification information that has been inserted in the data by the identification information inserting unit.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based upon and claims the benefit of priorityunder 35 USC 120 and 365(c) of PCT application JP2009/054682 filed inJapan on Mar. 11, 2009, the entire contents of which are incorporatedherein by reference.

FIELD

The embodiments discussed herein are related to a system fortransmitting and receiving data including encoded video imageinformation.

BACKGROUND

Recently, there is increased demand for streaming video image data in areal-time manner via various communication means such as the Internet.Particularly recently, in digital broadcasting and Internet television,it has become common to perform real-time data distribution by transportstreaming specified by MPEG2, which is a technology of compressing andmultiplexing video images and audio (see patent document 1).

When the transport stream specified by MPEG2 is received and the videoimages and audio are reproduced, multiple TS (Transport Stream) packetsincluding information necessary to start reproducing are received, andthen the video images and audio are reproduced with the use ofinformation included in the TS packets.

Patent document 1: Japanese Laid-Open Patent Publication No. 2008-245061

However, when video images and audio are reproduced by the abovetechnology, it takes a certain amount of time until all of the TSpackets including information needed to start reproduction are received.Therefore, a time lag occurs from the start of data reception until thestart of data reproduction.

SUMMARY

According to an aspect of the present invention, a data transmittingdevice for transmitting data including video image information that isinter-frame encoded, includes an identification information insertingunit configured to insert, in the data to be transmitted by the datatransmitting device, video image identification information foridentifying the video image information included in the data; and avideo image information inserting unit configured to insert the videoimage information in the data to be transmitted by the data transmittingdevice, wherein the video image information inserting unit inserts inthe data the video image information that has been inter-frame encoded,behind the video image identification information that has been insertedin the data by the identification information inserting unit.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe appended claims. It is to be understood that both the foregoinggeneral description and the following detailed description are exemplaryand explanatory and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is for describing a structure of a TS packet;

FIG. 2 is for describing a structure of a PAT (Program AssociationTable) packet;

FIG. 3 is for describing a structure of a PMT (Program Map Table)packet;

FIG. 4 illustrates an example of a hardware configuration of a datatransmitting device and a data receiving device according to the presentembodiment;

FIG. 5 is for describing the principle of the operation of the datatransmitting device according to the present embodiment;

FIG. 6 is for describing the configuration of a packet to be transmittedoutside from the data transmitting device according to the presentembodiment;

FIG. 7 is for describing a structure of an RTP (Real-time TransportProtocol) header;

FIG. 8 is a flowchart of a multiplex process performed by the datatransmitting device according to the present embodiment;

FIG. 9 is a flowchart of an external transmission process performed bythe data transmitting device according to the present embodiment;

FIG. 10 is a functional block diagram of a data transmitting deviceaccording to the conventional technology;

FIG. 11 illustrates data that is transmitted or received in time seriesaccording to the conventional technology;

FIG. 12 illustrates data that is transmitted or received in time seriesaccording to the present embodiment; and

FIG. 13 is for describing the principle of the operation of the datareceiving device according to the present embodiment.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will be explained withreference to accompanying drawings. In the following data transmittingdevice and data receiving device according to the present embodiment,the transport stream specified by MPEG2 is the processing target;however, the present invention is not limited thereto.

Process of Reproducing Video Images and Audio Based on Transport StreamSpecified by MPEG2

In a transport stream (hereinafter, “TS”) specified by MPEG2, pluralvideo images (MPEG2 standard, H.264 standard, etc.) and audio(MPEG1-Layer2 standard, MPEG-AAC standard, etc.) are multiplexed in asingle TS.

In order to reproduce video images and audio from a TS, first, a TSpacket of a PAT (Program Association Table) is extracted from thereceived TS, and a PID (Packet ID) of the PMT (Program Map Table) fromthe data of the PAT. The PAT is for storing a list of programs includedin the TS as a PID list of PMT. The PID of PAT is always zero. The aboveprocess is performed by referring to the “PID” indicated in FIG. 1 andthe “program_map_PID” indicated in FIG. 2.

Next, to reproduce video images, TS packets of PMT are extracted fromthe received TS based on the acquired PIDs of PMT, and the PIDs of thevideo images and audio are acquired from the data of the PMT. The PMT isfor storing respective PIDs of images and audio included in theprograms, and the above process is performed by referring to the“elementary_PID” indicated in FIG. 3.

In order to reproduce video images, the TS packets of the video imagesand audio are extracted from the received TS based on the PIDs of theacquired video images and audio, and the data areas of the TS packets ofthe video images and audio are connected to reproduce an elementarystream. An elementary stream (hereinafter, “ES”) is the minimum unit ofencoded images and audio.

As information for reproducing an ES from TS packets of video images andaudio as above, there is a “payload_unit_start_indicator” in the TSpackets. When the “payload_unit_start indicator” of a TS packet is“one”, it means that the corresponding TS packet is the leading packetof PES (Packetized ES) packets in ES. When the“payload_unit_start_indicator” of a TS packet is “zero”, it means thatthe corresponding TS packet is data located in the midstream of the PESpackets. The TS packets up to the one immediately before the“payload_unit_start_indicator” changes from zero to one are extracted,and the extracted TS packets are connected together to reproduce an ESof video images and audio.

In the ES of the video images, video image information items havingdifferent video image encoding methods are inserted to enhance thecompression efficiency. Examples of the video image information itemsare an I-Picture (encoded video image in a frame), a P-Picture(inter-frame forward directional prediction encoded video image), and aB-Picture (bidirectional prediction encoded video image). However, whenreproducing the ES of video images, the first video image needs to bereproduced based on the I-picture without using information of precedingor succeeding video image frames.

Furthermore, in order to reproduce a TS of video images and audio in areal-time manner, there are cases where clock signals in synchronizationwith a PCR (Program Clock Reference) transmitted by an encoder of the TStransmitting side, are generated by a decoder of the TS receiving side,and the video images and audio are reproduced in synchronization withthe generated clock signals. The PCR is transmitted from the TStransmitting side as TS packets, and PIDs of PCR packets are indicatedin the PMT.

FIG. 10 is a functional block diagram of a data transmitting deviceaccording to the conventional technology. As illustrated in FIG. 10, inthe data transmitting device according to the conventional technology,various packets are multiplexed by respective units at arbitrarytimings. For example, a PAT multiplexing control unit multiplexes PATpackets, a PMT multiplex control unit multiplexes PMT packets, a PCRmultiplex control unit multiplexes PCR packets, a video image multiplexcontrol unit multiplexes packets including I-Pictures, and an audioimage multiplex control unit multiplexes packets including audioinformation.

Accordingly, there is no knowing of the order in which these packets mayappear in the TS received by the TS receiving device. There may be oneor more TS packets between PAT packet and the PMT packet, between thePMT packet and the PCR packet, and between the PCR packet and theI-Picture packet.

When an instruction to start reproducing video images is received, thedata receiving device first waits to receive a PAT packet. When a PATpacket is received, the data receiving device waits for a certain amountof time to receive a packet having the same PID as that of the PMTpacket indicated in the received PAT packet. Similarly, when referringto a PCR packet and a packet including an I-Picture, the data receivingdevice waits for a certain amount of time to receive such a packet.Thus, it takes time, from when an instruction to start reproduction isreceived to when reproduction actually starts.

FIG. 11 illustrates an example of a data reception process performed bya data receiving device to which the conventional technology is applied.As illustrated in FIG. 11, at the data receiving unit, I-Picture packetsare received at intervals of X, and any one of PAT packets, PMT packets,and PCR packets are received at intervals of Y, where X and Y aredifferent reception intervals. For example, the reception interval X is500 msec, and the reception interval Y is 100 msec, so that thereception interval X is longer than the reception interval Y. In thiscase, in consideration of the characteristics of the packets asdescribed above, in order for the data receiving device to startdecoding video information based on I-Picture packets, it may take alength of time that is greater than or equal to X from the start of datareception.

A data transmitting device 100 disclosed herein transmits. TS packets inthe order of a PAT packet, a PMT packet, a PCR packet, and an I-Picturepacket. Therefore, it is possible for the receiving side to smoothlyexecute a reproduction process. Accordingly, when multiplexed videoimages and audio are reproduced from TS specified by MPEG2, thereceiving side acquires TS packets in the order of a PAT packet, a PMTpacket, a PCR packet, and an I-Picture packet, so that the reproductionprocess is smoothly performed. That is to say, when the TS packets areacquired in the stated order, it is possible to reduce the time takenfrom when data is received to when the reproduction process is startedat receiving side.

Hardware Configuration of Data Transmitting Device According to PresentEmbodiment

With reference to FIG. 4, a description is given of an example of ahardware configuration of the data transmitting device 100 according tothe present embodiment. FIG. 4 illustrates an example of a hardwareconfiguration of the data transmitting device 100.

The data transmitting device 100 illustrated in FIG. 4 includes a CPU(Central Processing Unit) 310, a ROM (Read-Only Memory) 320, a RAM(Random Access Memory) 330, a HDD (Hard Disc Drive) 340, acommunications I/F (Interface) 350, and a display device 360.

The CPU 310 executes programs stored in the ROM 320, performscalculation processes on data loaded in the RAM 330 according tocommands of the programs, and controls the entire data transmittingdevice 100. The ROM 320 stores programs executed by the CPU 310 anddata. The RAM 330 is where programs to be executed and data are loadedwhen the CPU 310 executes programs stored in the ROM 320. During thecalculation, the operation data is temporarily held in the RAM 330. TheHDD 340 stores the OS which is basic software and application programsaccording to the present embodiment in association with relevant data.

The communications I/F 350 is for exchanging data with anotherperipheral device (a receiving device for receiving a transport streamspecified by MPEG2) provided with a communications control functionconnected to the data transmitting device 100 via a communicationsnetwork (wired or wireless). The display device 360 is configured withkey switches including hard keys and an LCD (Liquid Crystal Display).The display device 360 functions as an interface when the user usesfunctions of the data transmitting device 100 and the user sets varioussettings.

As indicated in FIG. 4, a data receiving device 280 also includes a CPU410, a ROM 420, a RAM 430, an HDD 440, a communications I/F 450, and adisplay device 460, similar to the data transmitting device 100.

The respective units and elements included in the data transmittingdevice 100 and the data receiving device 280 may be implemented as theCPU 310 and the CPU 410 respectively execute programs corresponding tounits and elements stored in the ROM 320 and the ROM 420 or the HDD 340and the HDD 440. Furthermore, the respective units and elements includedin the data transmitting device 100 and the data receiving device 280may be implemented as hardware for performing processes relevant to theunits and elements.

Principle of Operation of Data Transmitting Device According to PresentEmbodiment

With reference to FIG. 5, a description is given of the principle of theoperation of the data transmitting device 100. FIG. 5 is for describingthe principle of the operation of the data transmitting device 100.

The data transmitting device 100 illustrated in FIG. 5 includes amultiplexing unit 110, a PAT/PMT multiplex control unit 120, a PATmultiplex control unit 140, a PMT multiplex control unit 160, a PCRmultiplex control unit 180, and timers 150, 170, and 190. Furthermore,the data transmitting device 100 includes a video image multiplexcontrol unit 200, a video image encoding unit 220, an audio multiplexcontrol unit 240, an audio encoding unit 250, and a TS transmitting unit260.

The data transmitting device 100 is connected to the data receivingdevice 280 via an IP network 270, for example, and transmits a transportstream specified by MPEG2 to the data receiving device 280. The datareceiving device 280 decodes the received transport stream, andreproduces video images and audio. The data transmitting device 100 andthe data receiving device 280 are included in a data transmitting andreceiving system 600.

The multiplexing unit 110 multiplexes predetermined information in theTS, in accordance with instructions from the PAT/PMT multiplex controlunit 120, the PAT multiplex control unit 140, the PMT multiplex controlunit 160, the PCR multiplex control unit 180, the video image multiplexcontrol unit 200, and the audio multiplex control unit 240.

When a predetermined report is received from the timer 150, the PATmultiplex control unit 140 instructs the multiplexing unit 110 tomultiplex a PAT packet in the TS. The timer 150 sends reports to the PATmultiplex control unit 140 at appropriate time intervals.

When a predetermined report is received from the timer 170, the PMTmultiplex control unit 160 instructs the multiplexing unit 110 tomultiplex a PMT packet in the TS. The timer 170 sends reports to the PMTmultiplex control unit 160 at appropriate time intervals.

When a predetermined report is received from the timer 190, the PCRmultiplex control unit 180 instructs the multiplexing unit 110 tomultiplex a PCR packet in the TS. The timer 190 sends reports to the PCRmultiplex control unit 180 at appropriate time intervals.

The audio encoding unit 250 generates an ES by encoding audio to bemultiplexed in the TS, and reports the ES to the audio multiplex controlunit 240. The audio encoding unit 250 reports the generated ES to theaudio multiplex control unit 240, and reports the timing formultiplexing the ES in the TS.

The audio multiplex control unit 240 instructs the multiplexing unit 110to multiplex an ES relevant to audio reported from the audio encodingunit 250 in the TS, based on a timing reported from the audio encodingunit 250.

The video image encoding unit 220 generates an ES by encoding videoimages to be multiplexed in the TS, and reports the ES to the videoimage multiplex control unit 200. Furthermore, the video image encodingunit 220 reports the generated ES to the video image multiplex controlunit 200, and also reports the timing of multiplexing the ES in the TS.

The video image multiplex control unit 200 instructs the multiplexingunit 110 to multiplex the ES relevant to the video image reported fromthe video image encoding unit 220 in the TS, based on the timingreported from the video image encoding unit 220.

The video image multiplex control unit 200 and the video image encodingunit 220 include a multiplex timing reporting unit 210 and a multiplextiming reporting unit 230, respectively. The multiplex timing reportingunit 210 and the multiplex timing reporting unit 230 send, to thePAT/PMT multiplex control unit 120, a notification that the I-Picturepacket is to be multiplexed in the TS, or a report indicating the timingof multiplexing the I-Picture packet in the TS.

As illustrated in FIG. 5, the multiplex timing reporting unit 210 andthe multiplex timing reporting unit 230 are respectively provided in thevideo image multiplex control unit 200 and the video image encoding unit220. In another example, the multiplex timing reporting unit (210 or230) may only be included in either one of the video image multiplexcontrol unit 200 or the video image encoding unit 220.

The PAT/PMT multiplex control unit 120 instructs the multiplexing unit110 to multiplex PAT packets and PMT packets in the TS. Specifically,the PAT/PMT multiplex control unit 120 instructs the multiplexing unit110 to multiplex the packets in the order of a PAT packet and a PMTpacket.

The video image multiplex control unit 200 instructs the multiplexingunit 110 to multiplex the I-Picture packets immediately behind the PMTpacket that is multiplexed in the TS based on the multiplex instructionby the PAT/PMT multiplex control unit 120.

According to one embodiment, the PAT/PMT multiplex control unit 120instructs the multiplexing unit 110 to multiplex the PAT packet, the PMTpacket, and the PCR packet in the TS. In this case, the PAT/PMTmultiplex control unit 120 gives an instruction to multiplex the packetsin the order of the PAT packet, the PMT packet, and the PCR packet.

Then, the video image multiplex control unit 200 instructs themultiplexing unit 110 to multiplex the I-Picture packets immediatelybehind the PCR packet that is multiplexed in the TS based on themultiplex instruction by the PAT/PMT multiplex control unit 120.

Furthermore, the PAT/PMT multiplex control unit 120 includes a multiplextiming acquiring unit 130. The multiplex timing acquiring unit 130acquires a report of multiplexing I-Picture packets in the TS reportedby the multiplex timing reporting units 210, 230, or a report of thetiming for multiplexing the I-Picture packets in the TS.

According to one embodiment of the PAT/PMT multiplex control unit 120,when the multiplex timing acquiring unit 130 acquires either one of theabove reports, the PAT/PMT multiplex control unit 120 gives the abovedescribed multiplex instruction to the multiplexing unit 110.

FIG. 12 is for describing an overview of the TS that is transmitted bythe data transmitting device 100 (or received by the data receivingdevice 280). As illustrated in FIG. 12, the data transmitting device 100multiplexes the packets in the TS, in the order of the PAT packet, thePMT packet, the PCR packet, and the I-Picture packet, based on theprocesses by the PAT/PMT multiplex control unit 120 and the video imagemultiplex control unit 200 (hereinafter, “multiplex process”). Thepackets that have been multiplexed by the PAT/PMT multiplex control unit120 are surrounded by dashed lines in FIG. 12. Thus, by performing themultiplex process, the data transmitting device 100 smoothly performsthe process of reproducing the transport stream specified by MPEG2 atthe data receiving device 280. At the data receiving device 280, afterstarting to receive the TS, the data receiving device 280 startsdecoding the video image information within the reception interval X(for example, 500 msec) of I-Picture packets. That is to say, comparingthe present embodiment with the conventional technology illustrated inFIG. 11, by using the data transmitting device 100 and the datareceiving device 280, it is possible for the data receiving device 280to start decoding the video. image information within a relatively shortperiod of time after starting to receive the TS.

The TS transmitting unit 260 sends, outside the data transmitting device100, the TS that has been multiplexed at the multiplexing unit 110. Asillustrated in FIG. 6, the TS transmitting unit 260 sends, outside thedata transmitting device 100, the PAT packet, the PMT packet, the PCRpacket, and the I-Picture packets that have been multiplexed in the TS,without changing the order of these packets.

Furthermore, as illustrated in FIG. 6, when the TS transmitting unit 260transmits the TS outside via the IP network 270, the packets may bearranged in the order of the PAT packet, the PMT packet, the PCR packet,and the I-Picture packets immediately behind the header part of thetransmission packet. The data transmitting device 100 transmits dataused for a TS reproduction process at the data receiving device 280 inan appropriate order, based on a process performed by the TStransmitting unit 260. Therefore, it is possible for the data receivingdevice 280 to smoothly perform the process of reproducing the TS.Furthermore, when the TS transmitting unit 260 uses RTP (Real-timeTransport Protocol) to transmit the TS outside, the following featuremay be added. Specifically, in addition to the above requirements, amarker flag, which is used for identifying a transmission packet thathas undergone the multiplex process, may be attached inside the headerpart of the RTP packet. The above marker flag is attached to theposition indicated by “M” in FIG. 7. This process is performed at thedata transmitting device 100 and the data receiving device 280 monitorsthe marker flags, and therefore the position where I-Picture is to bereproduced is easily detected when performing the reproduction process.

Meanwhile, as illustrated in FIG. 13, the data receiving device 280includes a data receiving unit 510, a data sorting unit 520, and a datadecoding unit 530. The data receiving unit 510 receives a TS transmittedfrom the data transmitting device 100. The data sorting unit 520 sortsthe TS packets into video image information, audio information, andother information, based on data attribute identification informationincluded in the PAT packet and the PMT packet extracted from thereceived TS packet. The data decoding unit 530 decodes the informationthat has been sorted by the data sorting unit 520.

The data receiving unit 510 monitors the marker flags attached to theRTP packets by the TS transmitting unit 260. When a marker flag isdetected, the data receiving unit 510 determines that the received TShas undergone the multiplex process. Then, the data receiving unit 510executes the decoding process of video image information, on the TSpackets following the received TS determined as being a TS that hasundergone the multiplex process. Accordingly, when the reproductionprocess is performed at the data receiving device 280, the positionwhere I-Picture is to be reproduced is easily detected. In the datareceiving device 280, after the position where I-Picture is to bereproduced is detected, only the information processing for decoding isto be performed. Therefore, it is possible to reduce the load of thedata attribute identification process on the TS packet at the datareceiving device 280.

In the present embodiment, the PAT/PMT multiplex control unit 120, thevideo image multiplex control unit 200 or the video image encoding unit220, the multiplex timing acquiring unit 130, and the TS transmittingunit 260 correspond to the identification information inserting unit,the video image information inserting unit, the insertion timingacquiring unit, and the data transmitting unit, respectively.

Example Process Performed by Data Transmitting Device According toPresent Embodiment

With reference to FIGS. 8 and 9, a description is given of a processexample performed by the data transmitting device 100 according to thepresent embodiment.

(1) Example of Multiplex Process Performed by Data Transmitting DeviceAccording to Present Embodiment

With reference to FIG. 8, a description is given of an example of amultiplex process performed by the data transmitting device 100. FIG. 8is a flowchart of a multiplex process performed by the data transmittingdevice 100.

In step S10, the data transmitting device 100 starts a multiplex processof TS. In step S20, the data transmitting device 100 determines whethera timing to multiplex the I-Picture packets has approached.Specifically, in step S20, when the multiplex timing acquiring unit 130receives a report of a timing to multiplex the I-Picture packets fromthe video image multiplex control unit 200 or the video image encodingunit 220 (YES in step S20), the process proceeds to step S30. Meanwhile,in step S20, when the multiplex timing acquiring unit 130 does notreceive such a report (NO in step S20), the process proceeds to stepS40.

In step S30, the PAT/PMT multiplex control unit 120 instructs themultiplexing unit 110 to multiplex the packets in the TS in the order ofthe PAT packet, the PMT packet, and the PCR packet. In step S30, themultiplexing unit 110 multiplexes the PAT packet, the PMT packet, andthe PCR packet in accordance with the instruction.

In step S40, the data transmitting device 100 determines whether it is atiming to multiplex the PAT packet. Specifically, in step S40, when thePAT multiplex control unit 140 receives a report from the timer 150 (YESin step S40), in step S50, the PAT multiplex control unit 140 instructsthe multiplexing unit 110 to multiplex the PAT packet in the TS. Then,in step S50, the multiplexing unit 110 multiplexes the PAT packet in theTS. In step S40, when the PAT multiplex control unit 140 does notreceive a report from the timer 150 (NO in step S40), the processproceeds to step S60.

In step S60, the data transmitting device 100 determines whether it is atiming to multiplex the PMT packet. Specifically, in step S60, when thePMT multiplex control unit 160 receives a report from the timer 170 (YESin step S60), in step S70, the PMT multiplex control unit 160 instructsthe multiplexing unit 110 to multiplex the PMT packet in the TS. Then,in step S70, the multiplexing unit 110 multiplexes the PMT packet in theTS. In step S60, when the PMT multiplex control unit 160 does notreceive a report from the timer 170 (NO in step S60), the processproceeds to step S80.

In step S80, the data transmitting device 100 determines whether it is atiming to multiplex the PCR packet. Specifically, in step S80, when thePCR multiplex control unit 180 receives a report from the timer 190 (YESin step S80), in step S90, the PCR multiplex control unit 180 instructsthe multiplexing unit 110 to multiplex the PCR packet in the TS. Then,in step S90, the multiplexing unit 110 multiplexes the PCR packet in theTS. In step S80, when the PCR multiplex control unit 180 does notreceive a report from the timer 190 (NO in step S80), the processproceeds to step S100.

In step S100, the data transmitting device 100 determines whether it isa timing to multiplex the encoded video images. Specifically, in stepS100, when the video image multiplex control unit 200 receives a reportindicating a timing for multiplexing the video images from the videoimage encoding unit 220 (YES in step S100), the process proceeds to step5110. In step S100, when the video image multiplex control unit 200 doesnot receive a report indicating a timing for multiplexing the videoimages from the video image encoding unit 220 (NO in step S100), theprocess proceeds to step S120.

In step S110, the video image multiplex control unit 200 instructs themultiplexing unit 110 to multiplex, in the TS, the ES relevant to thevideo images reported from the video image encoding unit 220.Particularly, when the result of step S20 is YES, in step S110, thevideo image multiplex control unit 200 instructs the multiplexing unit110 to multiplex the I-Picture packets reported form the video imageencoding unit 220, immediately behind the PCR packet multiplexed in theTS in step S30. Then, in step S110, the multiplexing unit 110 performsthe multiplex according to the instruction from the video imagemultiplex control unit 200.

In step S120, the data transmitting device 100 determines whether it isa timing to multiplex the encoded audio. Specifically, in step S120,when the audio multiplex control unit 240 receives a report indicating atiming for multiplexing the audio from the audio encoding unit 250 (YESin step S120), the process proceeds to step S130. In step S120, when theaudio multiplex control unit 240 does not receive a report indicating atiming for multiplexing the audio from the audio encoding unit 250 (NOin step S120), the process proceeds to step S140.

In step S130, the audio multiplex control unit 240 instructs themultiplexing unit 110 to multiplex, in the TS, the ES relevant to theaudio reported from the audio encoding unit 250. Then, in step S130, themultiplexing unit 110 performs the multiplex according to theinstruction from the audio multiplex control unit 240. In step S140, thedata transmitting device 100 ends the multiplex process in TS.

The data transmitting device 100 may perform the multiplex process basedon the PAT/PMT multiplex control unit 120 and the video image multiplexcontrol unit 200. Furthermore, by performing the multiplex process, itis possible for the data transmitting device 100 to smoothly perform theprocess of reproducing the TS specified MPEG2 at the data receivingdevice 280.

(2) Example of External Transmission Process Performed by DataTransmitting Device According to Present Embodiment

With reference to FIG. 9, a description is given of an example of anexternal transmission process performed by the data transmitting device100. FIG. 9 is a flowchart of an external transmission process performedby the data transmitting device 100.

In step S210, the data transmitting device 100 starts an externaltransmission process of TS. In step S220, when the data to be externallytransmitted (to be transmitted outside) is a TS that has undergone themultiplex process (YES in step S220), in step S230, the TS transmittingunit 260 raises an I-Picture transmission flag. Meanwhile, in step S220,when the data to be externally transmitted is a TS that has notundergone the multiplex process (NO in step S220), in step S260, the TStransmitting unit 260 saves the TS sent from the multiplexing unit 110by adding it to a TS that is temporarily saved in the RAM 330.

In step S240, when there is one or more temporarily saved TS that hasnot undergone the multiplex process (YES in step S240), in step S250,the TS transmitting unit 260 transmits outside all TS that have notundergone the multiplex process, with the use of UDP (User DatagramProtocol) or RTP.

In step S240, when there is not one temporarily saved TS that has notundergone the multiplex process (NO in step S240), in step S260, the TStransmitting unit 260 saves the TS that has been transmitted from themultiplexing unit 110 by adding it to a TS that is temporarily saved inthe RAM 330. When adding the TS to a temporarily saved TS, the TS's aresaved in an order that the TS transmitting unit 260 receives the TS'sfrom the multiplexing unit 110. By saving the TS's in this order, it ispossible to externally transmit the TS's in the order they aremultiplexed by the multiplexing unit 110.

In step S240, when there is one or more temporarily saved TS that hasnot undergone the multiplex process (YES in step S240), by transmittingthe TS at step S250, it is possible to dispose the PAT information (PATpacket) immediately behind the header part of the transmission packet.

In step S270, when the number of TS's temporarily saved in the RAM 330is within a predetermined number (YES in step S270), the process returnsto step S220. In step S270, when the number of TS's temporarily saved inthe RAM 330 exceeds a predetermined number (NO in step S270), theprocess proceeds to step S280.

In step S280, when the transmission mode of the external transmissionperformed by the TS transmitting unit 260 is UDP (YES in step S280), instep S290, the TS transmitting unit 260 uses UDP to transmit outside allof the temporarily saved TS's. In step S290, the TS transmitting unit260 transmits outside the PAT packet, the PMT packet, the PCR packet,and the I-Picture packets that have been multiplexed in the TS, withoutchanging this order.

The data transmitting device 100 transmits data used for a TSreproduction process at the data receiving device 280 in the appropriateorder, based on a process performed by the TS transmitting unit 260.Therefore, it is possible for the data receiving device 280 to smoothlyperform the process of reproducing the TS.

In step S280, when the transmission mode of the external transmissionperformed by the TS transmitting unit 260 is not UDP (NO in step S280),the process proceeds to step S300. In step S300, when an I-Picture flagis raised (YES in step S300), in step S310, the TS transmitting unit 260attaches, to the leading edge of a temporarily saved TS, an RTP headerhaving a marker flag indicating “1”.

In step S300, when an I-Picture flag is not raised (NO in step S300), instep S320, the TS transmitting unit 260 attaches, to the leading edge ofa temporarily saved TS, an RTP header having a marker flag indicating“0”.

In step S330, the TS transmitting unit 260 transmits outside thegenerated RTP packet, and in step 5340, the data transmitting device 100ends the external transmission process of TS. The data receiving device280 receives the TS transmitted by the data transmitting device 100, andmonitors the marker flag in the received RTP header, to detect aposition where I-Picture is to be reproduced.

At the data receiving device 280 that has received the packettransmitted by the data transmitting device 100, the PMT packet isreceived immediately after the PAT packet, the PCR packet is receivedimmediately after the PMT packet, and the I-Picture packet is receivedimmediately after the PCR packet. Accordingly, there is no need to waitfor a certain amount of time to receive a necessary packet afterreceiving a packet transmitted by a data transmitting device accordingto the conventional technology as described above. Furthermore, toinstall the data transmitting device 100, there is no need to change thefunctions or the hardware of the data receiving device 280 whatsoever.

Overview

With the data transmitting device according to one embodiment, when thedata receiving device reproduces video images based on encoded videoimage information transmitted from the data transmitting device, it ispossible to start the reproduction process within a short period of timefrom when the data receiving device starts receiving the data.

The present invention is not limited to the specific embodimentsdescribed herein, and variations and modifications may be made without.departing from the scope of the present invention.

According to an aspect of the present invention, a data transmittingdevice and a data transmitting and receiving system are provided, whichare capable of starting a reproduction process within a short length oftime from the start of data reception, when a receiver reproduces videoimages based on encoded video image information transmitted from thedata transmitting device.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A data transmitting device for transmitting dataincluding video image information that is inter-frame encoded, the datatransmitting device comprising: an identification information insertingunit configured to insert, in the data to be transmitted by the datatransmitting device, video image identification information foridentifying the video image information included in the data; and avideo image information inserting unit configured to insert the videoimage information in the data to be transmitted by the data transmittingdevice, wherein the video image information inserting unit inserts inthe data the video image information that has been inter-frame encoded,behind the video image identification information that has been insertedin the data by the identification information inserting unit.
 2. Thedata transmitting device according to claim 1, wherein theidentification information inserting unit includes an insertion timingacquiring unit configured to acquire, from the video image informationinserting unit, a report indicating that the video image informationthat has been inter-frame encoded is to be inserted in the data, theidentification information inserting unit inserts, in the data, thevideo image identification information and clock information in thestated order when the insertion timing acquiring unit acquires thereport, the clock information being used for synchronizing with a devicewith which the data is exchanged, and the video image informationinserting unit inserts, in the data, the video image information thathas been inter-frame encoded, immediately behind the clock informationthat has been inserted in the data by the identification informationinserting unit.
 3. The data transmitting device according to claim 2,further comprising: a data transmitting unit configured to transmit thedata outside the data transmitting device via an IP network, wherein thedata transmitting unit does not change the order of the video imageidentification information, the clock information, and the video imageinformation that has been inter-frame encoded in the data, and locatesthe video image identification information immediately behind a headerpart of a transmission packet, when transmitting the data.
 4. The datatransmitting device according to claim 3, wherein when the datatransmitting unit transmits the data with the use of an RTP (Real-timeTransport Protocol), the data transmitting unit attaches, in a headerpart of an RTP packet, a marker flag for identifying that thetransmission packet is relevant to the data including the video imageidentification information, the clock information, and the video imageinformation that has been inter-frame encoded in the stated order.
 5. Adata transmitting and receiving system comprising: the data transmittingdevice according to claim 1; and a data receiving device including adata receiving unit configured to receive the data transmitted by thedata transmitting device, a data sorting unit configured to extract thevideo image information from the data based on the video imageidentification included in the data received by the data receiving unit,and a data decoding unit configured to decode the video imageinformation that has been extracted by the data sorting unit.
 6. A datatransmitting and receiving system comprising: the data transmittingdevice according to claim 4; and a data receiving device including adata receiving unit configured to receive the data transmitted by thedata transmitting device, a data sorting unit configured to extract thevideo image information from the data based on the video imageidentification included in the data received by the data receiving unit,and a data decoding unit configured to decode the video imageinformation that has been extracted by the data sorting unit, whereinthe data receiving unit identifies whether the data of the transmissionpacket includes the video image identification information, the clockinformation, and the video image information that has been inter-frameencoded in the stated order, based on the marker flag in the header partof the RTP packet relevant to the data received by the data receivingunit.
 7. A non-transitory computer-readable storage medium with anexecutable data transmitting program stored therein, wherein the datatransmitting program instructs a processor of a data transmitting devicefor transmitting data including video image information that isinter-frame encoded to execute a method comprising: inserting, in thedata to be transmitted by the data transmitting device, video imageidentification information for identifying the video image informationincluded in the data; and inserting the video image information in thedata to be transmitted by the data transmitting device, wherein thevideo image information that has been inter-frame encoded is inserted inthe data, behind the video image identification information that hasbeen inserted in the data.
 8. The non-transitory computer-readablestorage medium according to claim 7, wherein the inserting of the videoimage identification information further includes acquiring a reportindicating that the video image information that has been inter-frameencoded is to be inserted in the data, the video image identificationinformation and clock information are inserted in the data in the statedorder when the report is acquired, the clock information being used forsynchronizing with a device with which the data is exchanged, and thevideo image information that has been inter-frame encoded is inserted inthe data, immediately behind the clock information that has beeninserted in the data.
 9. The non-transitory computer-readable storagemedium according to claim 8, further comprising: transmitting the dataoutside the data transmitting device via an IP network, wherein theorder of the video image identification information, the clockinformation, and the video image information that has been inter-frameencoded is not changed in the data, and the video image identificationinformation is located behind a header part of a transmission packet,when transmitting the data.
 10. The non-transitory computer-readablestorage medium according to claim 9, wherein when the data istransmitted with the use of an RTP (Real-time Transport Protocol), amarker flag is attached in a header part of an RTP packet, the markerflag being used for identifying that the data of the transmission packetincludes the video image identification information, the clockinformation, and the video image information that has been inter-frameencoded in the stated order.
 11. A data transmitting device fortransmitting a transport stream specified by MPEG2, the datatransmitting device comprising: a PAT/PMT multiplex control unitconfigured to multiplex PAT (Program Association Table) informationincluding list information of programs relevant to reproducing thetransport stream, and PMT (Program Map Table) information includingidentification information of images and audio corresponding to theprograms, as the transport stream; and a video image multiplex controlunit configured to multiplex encoded video image information as thetransport stream, wherein the PAT/PMT multiplex control unit multiplexesthe PAT information and the PMT information in the stated order, and thevideo image multiplex control unit multiplexes I-Picture informationbehind the PMT information that is multiplexed by the PAT/PMT multiplexcontrol unit.
 12. The data transmitting device according to claim 11,wherein the PAT/PMT multiplex control unit includes a multiplex timingacquiring unit configured to acquire, from the video image multiplexcontrol unit, a report indicating that the I-Picture information is tobe multiplexed, the PAT/PMT multiplex control unit multiplexes the PATinformation, the PMT information, and PCR (Program Clock Reference)information in the stated order when the multiplex timing acquiring unitacquires the report, the PCR information being used for synchronizingwith a device with which data of the transport stream is exchanged, andthe video image multiplex control unit multiplexes the I-Pictureinformation immediately behind the PCR information that is multiplexedby the PAT/PMT multiplex control unit.
 13. The data transmitting deviceaccording to claim 12, further comprising: a TS transmitting unitconfigured to transmit the transport stream outside the datatransmitting device via an IP network, wherein the TS transmitting unitdoes not change the order of the PAT information, the PMT information,the PCR information, and the I-Picture information in the transportstream, and locates the PAT information immediately behind a header partof a transmission packet, when transmitting the transport stream outsidethe data transmitting device.
 14. The data transmitting device accordingto claim 13, wherein when the TS transmitting unit transmits thetransport stream outside the data transmitting device with the use of anRTP (Real-time Transport Protocol), the TS transmitting unit attaches,in a header part of an RTP packet, a marker flag for identifying thatthe transmission packet is relevant to the transport stream in which theI-Picture information is multiplexed immediately behind the PCRinformation.